The present invention relates to methods used in the wet painting or in the powder coating of an object for accelerating the drying of the painted surface of the object or of the polymerization of the powder coating thereof.
Heat is required in connection with both industrial type wet painting and electrostatic powder coating of objects. In the wet painting of objects, the application of heat increases the drying or reaction speed of the paint while in powder coating, the application of heat results in the polymerization of the powder coating. In the case of wet painting, the temperature of the object is usually raised to a value in the range of about 60.degree. to 80.degree. C. after both an intermediate painting stage as well as after the finish painting stage. On the other hand, in the case of powder coating, the temperature of the object is raised to the polymerization temperature which is generally in the range of about 180.degree. to 200.degree. C. In the latter technique, the object is usually raised to this temperature and maintained at such temperature for only about 15 minutes.
In the past, the elevated temperatures required by the wet painting and powder coating techniques have been obtained by resistance type circulating-air ovens or through the application of infra-radiation. Laser radiation has also been used to some extent in connection with the polymerization of powder coating on thin sheet objects.
These conventional techniques have drawbacks in that a large amount of heat energy is required to elevate the objects to the required temperatures. Moreover, the objects to be painted or coated must be shifted from place to place during the procedure. Furthermore, relatively large areas and specialized equipment are required for heating the painted or coated objects.